1. Field of the Invention
The present invention relates to an image forming apparatus.
2. Description of the Related Art
A color printer is one of conventional image forming apparatuses such as printers, copying machines, facsimile machines and composite structure of these, i.e., multifunction printers (MFP). A color printer performs an electrophotographic image forming process. A charging roller charges the surface of a photoconductive drum. An LED head illuminates the charged surface of the photoconductive drum to form an electrostatic latent image. A thin layer of toner formed on a developing roller is deposited to the electrostatic latent image by the Coulomb force, thereby forming a toner image on the photoconductive drum. A transfer roller transfers the toner image onto paper. A cleaning unit removes the toner remaining on the photoconductive drum after transfer.
The paper having the toner image on it advances to a fixing unit where the toner image is fused into the paper.
A temperature sensor detects the temperature of the fixing unit. The temperature of the fixing unit is controlled in accordance with the detection output of the temperature sensor, so that the temperature of the fixing unit is within a predetermined range.
A fixing unit needs to generate a large amount of heat for printing on a variety of print paper at high speed. In addition, the fixing unit is disposed close to a photoconductive drum for compact design of the printer. Thus, the toner in a developing unit may melt due to the heat from the fixing unit.
A toner for high speed printing has a low-melting point, and therefore increases the chance of the toner melting due to the heat from the fixing unit. The result is a poor print quality.